1. Field of the Invention
The present invention relates to a twin clutch type gear transmission which includes an even-numbered-gear-change gear transmission mechanism which includes a plurality of even-numbered gear-change gear trains which can be selectively established, an odd-numbered-gear-change gear transmission mechanism which includes a plurality of odd-numbered gear-change gear trains which can be selectively established, and a pair of clutches which is capable of individually changing over the disconnection and the connection of power transmission between input shafts which both gear transmission mechanisms include respectively and a power source, and more particularly to an improvement of a speed change control method for such a twin clutch type gear transmission.
2. Description of Background Art
In Japanese Patent No. 3598998, for example, there has been known a twin clutch type gear transmission in which a pair of clutches which individually correspond to first and second gear-change stage groups which are divided in two are brought into a connection state in a usual operation condition, and a desired speed change ratio is obtained by selectively establishing one of a plurality of gear-change gear trains which the first and second gear-change stage groups respectively include.
However, the twin clutch type gear transmission which is disclosed in Japanese Patent No. 3598998, in the usual operation condition, both clutches are brought into the connection state and hence, to establish the gear train for a next gear-change stage at the time of performing the speed-change changeover, it is necessary to disconnect one clutch. In this case, not only the speed-change responsiveness is lowered correspondingly to the disconnection of one clutch but also a friction loss in a usual operation condition is increased and hence, the fuel consumption of an engine is increased and, at the same time, a gear-change shock is large and hence, a rider cannot enjoy comfortable riding attributed to the large gear change shock.